环加成反应是有机协同反应的重要类型。通常可分为同面——同面(m_sm_s~′]、同面——异面[m_sm_a~′]、异面——同面[m_am_s~′]和异面——异面[m_am_a~′]四种,正如下面图示:一、局部对称群和能量算符两个乙烯分子的环加成反应的四种类型可由下图描绘:每对乙烯分子中的碳原子 Cycloaddition reaction is an important type of organic synergistic reaction. Can usually be divided into the same surface - the same surface (m_sm_s ~ ’], the same surface - different surface [m_sam_a ~’], the same surface [m_am_s ~ ’] ] Four, as shown below: First, the local symmetry group and the energy operator Two ethylene molecules of the cycloaddition reaction of the four types can be described by the following figure: Each pair of carbon atoms in the ethylene molecule